Allowance for Credit Losses (Portfolio Credit Quality) (Details) $ in Thousands	Mar. 31, 2023 USD ($) loan	Dec. 31, 2022 USD ($)
Loan portfolio by credit quality indicator
2023	$ 1,072,045
2022	2,703,074	$ 3,048,975
2021	1,773,923	2,081,483
2020	828,049	988,625
2019	473,803	543,277
2018/Prior	680,879	468,848
Prior		299,395
Total loans	$ 7,531,773	7,430,603
Commercial real estate: farmland & commercial
Loan portfolio by credit quality indicator
Number of loans downgraded \| loan	2
Commercial, financial and agricultural
Loan portfolio by credit quality indicator
Total loans	$ 4,370,745	4,373,373
Commercial, financial and agricultural \| Domestic \| Commercial.
Loan portfolio by credit quality indicator
2023	264,131
2022	589,634	766,789
2021	453,286	525,241
2020	87,778	97,498
2019	32,500	35,917
2018/Prior	70,773	43,841
Prior		29,468
Total loans	1,498,102	1,498,754
Commercial, financial and agricultural \| Domestic \| Commercial. \| Pass
Loan portfolio by credit quality indicator
2023	263,913
2022	530,585	736,462
2021	452,955	524,879
2020	87,039	96,401
2019	32,481	35,917
2018/Prior	68,318	43,792
Prior		29,464
Total loans	1,435,291	1,466,915
Commercial, financial and agricultural \| Domestic \| Commercial. \| Special Review
Loan portfolio by credit quality indicator
2022	371	377
2021	201	213
Total loans	572	590
Commercial, financial and agricultural \| Domestic \| Commercial. \| Watch List - Substandard
Loan portfolio by credit quality indicator
2023	218
2022	28,889	161
2021	130	149
2020		143
2019	19
2018/Prior	2,454	49
Total loans	31,710	502
Commercial, financial and agricultural \| Domestic \| Commercial. \| Watch List - Doubtful
Loan portfolio by credit quality indicator
2022	29,789	29,789
2020	739	954
2018/Prior	1
Prior		4
Total loans	30,529	30,747
Commercial, financial and agricultural \| Domestic \| Commercial real estate: farmland & commercial
Loan portfolio by credit quality indicator
2023	294,941
2022	795,136	833,401
2021	539,297	584,381
2020	357,035	511,194
2019	229,067	232,633
2018/Prior	347,623	325,214
Prior		81,295
Total loans	2,563,099	2,568,118
Commercial, financial and agricultural \| Domestic \| Commercial real estate: farmland & commercial \| Pass
Loan portfolio by credit quality indicator
2023	294,941
2022	723,848	811,117
2021	534,498	584,134
2020	353,714	456,200
2019	228,974	232,537
2018/Prior	336,205	325,214
Prior		81,295
Total loans	2,472,180	2,490,497
Commercial, financial and agricultural \| Domestic \| Commercial real estate: farmland & commercial \| Special Review
Loan portfolio by credit quality indicator
2022	173	2,855
2020	835	842
Total loans	1,008	3,697
Commercial, financial and agricultural \| Domestic \| Commercial real estate: farmland & commercial \| Watch List - Pass
Loan portfolio by credit quality indicator
2022	16,986	17,060
2021	243	247
Total loans	17,229	17,307
Commercial, financial and agricultural \| Domestic \| Commercial real estate: farmland & commercial \| Watch List - Substandard
Loan portfolio by credit quality indicator
2022	54,038	2,275
2021	4,556
2020	2,486	54,152
2019	93	96
2018/Prior	11,212
Total loans	72,385	56,523
Commercial, financial and agricultural \| Domestic \| Commercial real estate: farmland & commercial \| Watch List - Doubtful
Loan portfolio by credit quality indicator
2022	91	94
2018/Prior	206
Total loans	297	94
Commercial, financial and agricultural \| Domestic \| Commercial real estate: multifamily
Loan portfolio by credit quality indicator
2023	45,117
2022	125,140	127,797
2021	50,142	87,469
2020	58,802	59,035
2019	11,427	12,026
2018/Prior	18,916	5,490
Prior		14,684
Total loans	309,544	306,501
Commercial, financial and agricultural \| Domestic \| Commercial real estate: multifamily \| Pass
Loan portfolio by credit quality indicator
2023	45,117
2022	125,030	127,680
2021	50,142	87,469
2020	58,802	59,035
2019	11,427	12,026
2018/Prior	18,916	5,490
Prior		14,684
Total loans	309,434	306,384
Commercial, financial and agricultural \| Domestic \| Commercial real estate: multifamily \| Watch List - Doubtful
Loan portfolio by credit quality indicator
2022	110	117
Total loans	110	117
Obligations of states and political subdivisions
Loan portfolio by credit quality indicator
Total loans	2,081,138	1,989,669
Obligations of states and political subdivisions \| Domestic \| Commercial Real Estate: other construction and land development
Loan portfolio by credit quality indicator
2023	341,573
2022	860,150	933,657
2021	530,618	666,754
2020	186,718	173,918
2019	124,675	175,106
2018/Prior	37,404	35,069
Prior		5,165
Total loans	2,081,138	1,989,669
Obligations of states and political subdivisions \| Domestic \| Commercial Real Estate: other construction and land development \| Pass
Loan portfolio by credit quality indicator
2023	341,573
2022	840,168	913,675
2021	530,211	666,347
2020	186,626	173,824
2019	124,467	174,897
2018/Prior	37,404	35,069
Prior		5,165
Total loans	2,060,449	1,968,977
Obligations of states and political subdivisions \| Domestic \| Commercial Real Estate: other construction and land development \| Special Review
Loan portfolio by credit quality indicator
2019	208	209
Total loans	208	209
Obligations of states and political subdivisions \| Domestic \| Commercial Real Estate: other construction and land development \| Watch List - Doubtful
Loan portfolio by credit quality indicator
2022	19,982	19,982
2021	407	407
2020	92	94
Total loans	20,481	20,483
Real estate - mortgage
Loan portfolio by credit quality indicator
Total loans	858,909	865,994
Real estate - mortgage \| Domestic \| Residential: first lien
Loan portfolio by credit quality indicator
2023	71,028
2022	97,981	138,848
2021	76,754	82,826
2020	45,420	49,591
2019	32,016	40,985
2018/Prior	96,356	33,814
Prior		79,660
Total loans	419,555	425,724
Real estate - mortgage \| Domestic \| Residential: first lien \| Pass
Loan portfolio by credit quality indicator
2023	71,028
2022	97,907	138,771
2021	76,400	82,466
2020	45,354	49,591
2019	32,016	40,985
2018/Prior	96,356	33,814
Prior		79,660
Total loans	419,061	425,287
Real estate - mortgage \| Domestic \| Residential: first lien \| Watch List - Substandard
Loan portfolio by credit quality indicator
2021	354	360
2020	66
Total loans	420	360
Real estate - mortgage \| Domestic \| Residential: first lien \| Watch List - Doubtful
Loan portfolio by credit quality indicator
2022	74	77
Total loans	74	77
Real estate - mortgage \| Domestic \| Residential Junior Lien
Loan portfolio by credit quality indicator
2023	15,944
2022	91,262	92,256
2021	103,512	109,127
2020	86,758	91,130
2019	39,295	41,273
2018/Prior	102,583	21,975
Prior		84,509
Total loans	439,354	440,270
Real estate - mortgage \| Domestic \| Residential Junior Lien \| Pass
Loan portfolio by credit quality indicator
2023	15,944
2022	90,944	92,256
2021	103,512	108,815
2020	86,758	91,130
2019	39,295	41,273
2018/Prior	102,583	21,975
Prior		84,509
Total loans	439,036	439,958
Real estate - mortgage \| Domestic \| Residential Junior Lien \| Watch List - Doubtful
Loan portfolio by credit quality indicator
2022	318
2021		312
Total loans	318	312
Consumer
Loan portfolio by credit quality indicator
Total loans	43,390	41,592
Consumer \| Domestic
Loan portfolio by credit quality indicator
2023	12,176
2022	24,278	31,962
2021	4,412	6,603
2020	542	897
2019	344	489
2018/Prior	1,638	28
Prior		1,613
Total loans	43,390	41,592
Consumer \| Domestic \| Pass
Loan portfolio by credit quality indicator
2023	12,176
2022	24,278	31,962
2021	4,412	6,603
2020	542	897
2019	344	489
2018/Prior	1,638	28
Prior		1,613
Total loans	43,390	41,592
Foreign.
Loan portfolio by credit quality indicator
Total loans	177,591	159,975
Foreign. \| Foreign
Loan portfolio by credit quality indicator
2023	27,135
2022	119,493	124,265
2021	15,902	19,082
2020	4,996	5,362
2019	4,479	4,848
2018/Prior	5,586	3,417
Prior		3,001
Total loans	177,591	159,975
Foreign. \| Foreign \| Pass
Loan portfolio by credit quality indicator
2023	27,135
2022	119,493	124,265
2021	15,902	19,082
2020	4,996	5,362
2019	4,479	4,848
2018/Prior	5,586	3,417
Prior		3,001
Total loans	$ 177,591	$ 159,975

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